This invention relates to a rotary vane compressor for refrigerant fluids, and particularly to a configuration of the cylinder slot which accommodates the sliding or reciprocating vane for implementing improved lubrication, reduced wear and lubricant leakage, and the more expeditious flushing of abrasive wear particles.
A vertically installed refrigerant compressor of this general type and as described in Japanese patent application Ser. No. 57-165903 published May 12, 1984 is shown in FIGS. 1-3, and will only be briefly described as its overall construction and operation are well known and conventional. Essentially, a cylinder member 3 is clamped or bolted between a pair of opposing end plates within a sealed outer casing or shell 1. An eccentrically mounted cylindrical piston 4 is rotatably driven within the cylinder member by an electric motor via a crankshaft 2, and a blade-like vane 5 slidably mounted within a slot 7 in the cylinder member and biased inwardly by a spring 6 disposed within an aperture 8 bears against the surface of the piston and is reciprocatingly driven thereby during the rotation of the piston. The vane defines and separates high and low pressure chambers 18, 17 between the piston and the cylinder member. Refrigerant fluid drawn in on the low pressure side of the vane (just below the vane in FIG. 2) from an accumulator is compressed and discharged into the space 11 within the shell surrounding the motor and cylinder member, and a compressed fluid outlet pipe is provided at the top of the shell. The interior of the shell is thus maintained at a high pressure level, which is utilized to force lubricating oil 9 in a sump area at the bottom of the shell into the vane slot 7 to thus lubricate the sliding vane.
Frictionally induced wear and abrasion between the sliding vane 5 and its accommodating slot 7 within the cylinder member has long been a serious problem in compressors of this type. Such wear is enhanced by the differential pressure to which the vane is subjected between the high and low pressure chambers, which tends to push the inner tip of the vane downwardly as seen in FIG. 2, and by the frictional drag of the piston 4 as it rotates, which tends to draw the vane tip with it in the same direction. One result of such wear is the leakage of lubricating oil into the low pressure chamber along the lower wall of the slot 7 as viewed in FIG. 2 when the compressor is stopped, which is assisted by the partial vacuum drawn in such chamber. The presence of lubricating oil within the cylinder member 3 causes premature wear of the crankshaft bearings owing to the incompressibility of liquids, and such bearing failure sharply curtails the useful working life of the compressor.
One approach to reduce the problem of vane slot wear was to machine or otherwise form a lateral groove 10 in the wall of the slot 7 on the low pressure side of the vane, such slot assisting in the more uniform distribution of lubricating oil supplied to the slot via the spring aperture 8 and also enhancing the flushing away of abrasive metal particles attendant to the wearing of the slot-- particularly during the initial use of the compressor as the reciprocating vane establishes its seat in the slot. While such a groove represents a useful expedient, it is relatively costly to implement owing to the tight and restricted accessibility to its location, which considerably complicates the forming of the cylinder member 3 by conventional and less expensive sintering methods.